Preparation of bulky textiles



Filed June l2, .1958

INVENTOR.

wZON 023 526 N\ v M23 @255 0 fl M w v m uzEBw m .323 j nwm z 2,895,286 IPatented July 21, 1959 2,895,286 PREPARATION on BULKY TEXTILES Richard OConnell, El Cerrito, Califi, assignor to the United States of- America as represented by the Secretary of Agriculture Application June 12, 1958, Serial No. 741,708 3 Claims. c1. 57-456) '(Granted under Title 35, US. Code 1952 see. 266) A non-exclu sive,- irrevocable, royalty-free license inv the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to and has among its objects the provision of novel processes for producing wool textiles characterized by a bulkiness and loftiness not found in conventional woolen textiles. Also, the products of the invention display a softer hand and greater elasticity than conventional wooltextilcs and are particularly useful for the production of garments such as sweaters, socks,

.etc. where it is especially desirable to have'a soft, contour-conforming, elastice fabric. Theseand other objects and advantages of the invention will be evident from the following description taken in conjunction with the annexed drawing which schematically illustrates apparatus ably greater bulk, softness, and elasticity as compared to the original yarn.

Relaxation of the stretched and setyarn may be pre- United States Patent Ofiice I the contact of the yarn and swelling agent.

ceded by various mechanical steps, For example, the

stretched and set yarn may be woven or knitted into fabrics and the fabric as a whole subjected to the relaxationtreatment. This produces textiles of greater bulk, softer hand and greater elasticity than if constructed from the original untreated yarn. Another'alternative is 5 first passed through a 5% solution of formic acid in tank 2. The formic acid acts as a swelling agent in that it swells the fibers so that they may be stretched to a greater degree than possible with the untreatedwool. Next, the swelled yarnis stretched by the action of rollers 3 and 4, the latter set of rollers rotating at higher speed than the former to effectuate the stretching. The

stretched yarn is now conveyed past a set of infra-red lamps 5 which dry the yarn by vaporizing water and formic acid. During the drying, the yarn is maintained in its stretched state by operating rollers 6 at-the same speed as rollers 4. The yarn leaving rollers 6 is now in a stretched and set condition, that is, even if untensioned it will 'maintainits stretched length. The set-stretched yarn is thenpassed through plier 7 where it is twistedwith normal, untreated wool yarn from bobbin 8 to produce a multiple-ply yarn. I This composite yarn is then The shrinkage of the treated fibrous elements tends to also crimp and loop the untreated yarn elements much as the material of a drawstring pouch is puckered together when the drawstring is pulled taut, or as clothmay be shirred by pulling on basting threads running through the material. During this relaxation of the composite yarn, the speed of rollers -11 is maintained slower than rollers 10 so that the yarn is not under tension but may bulk upby crimping action without hindrance.

It will be found in a practice of the method exemplified above that many variations may be followed within the scope of the invention. For example, it is not essential to employand aqueous solution of formic acid to swell the wool'yarn; one may employ any agent which has the ability to swell wool fibers so that they may be stretched without breaking. Accordingly, one may employ aqueous solutions containing such agents as, for example, urea, guanidine hydrochloride, ammonium thiocyanate, formamide, acetamide, thiourea, sodium salicylate, urethane, phenol, lithium iodide, and so forth. Many other compounds which exhibit the ability to swell wool fibers so that they may be stretched without breaking are known to those skilled in the art and may be employed in the process of the invention.

Instead of swelling the yarn by passing it through a solution of a swelling agent it may be contacted with steam which acts as a swelling agent. In employing this modification of the process, the yarn is passed through a vessel where it is subjected to direct contact with steam. This swells the fibers so that the yarn may be stretched without breaking.

The stretching operation may be .performed after the yarn has been contacted with the swelling agent or during The latter type of procedure is preferred where the yarn is, swelled by subjecting it to'steam. In such case, the swelling and stretching may be accomplished together by passing the yarn through an elongated vessel wherein itis exposed to directcontact with steam and at the same time subjected .to tension to stretch it to the desired degree.

It is preferred that the swelling, agent employed be volatile sothat it is evaporated from the yarn during the drynig step. This eliminates the need for washing procedures as may be required where the agent is not vola-' tile. However, if a non-volatile swelling agent is employed it may be removed from the yarn after the stretching step by passing the yarn through a bath in which fresh water is circulated, the yarn being kept under tension to retain its stretched state during the washing operation.

The degree to which the swelled yarn is stretched may be varied to get dilferent degrees of bulkiness in the final product. Generally the greater degree of stretch applied, the greater thedegree of bulkiness imparted to the final product. In general, the yarn is stretched to a' length of to or more of its original length. If desired, the yarn may be treated with the swelling agent, stretched, re-treated with the swelling agent and stretched again. Such procedure is useful in some instances to get a greater degree of stretch than possible with a single treatment with the swelling agent.

In the drying stcp, it is not essential to subject the stretched yarn to infrared lamps; the'drying may be accomplished by any conventional technique. For example, the yarn may be subjected to a current of air heated to about 100200 F. It is of course essential that the yarn'be maintained under tension during the drying step so that it will be set in its stretched state.

The step of combining the set-stretched wool yarn with normal wool yarn is generally desirable as producing final products of especially bulky character. Variations however may be employed. For example the setstretched wool yarn may be plied with any textile yarns such as cotton, rayon, nylon, cellulose acetate, etc. In any event the shrinking of the set-stretched wool yarn during the'subsequent relaxing step will crimp the added yarns as described above. In anotheralternativeprocedure, the set-stretched wool yarn may be relaxed without the prior step ofplying with other yarns or the setstretched wool yarn may be formed by weaving, ,knit- Y Example I Wool yarn was immersed in a 5% solution of formic acid, then removed from the solution and stretched to 120% of its original length. While under tension to maintain it in the stretched state, the yarn was dried by exposure to infra-red lamps. Two lengths of the setstretched yarns were twisted together to form a twoply yarn. This yarnwhile in an untensioned state was contacted with steam. It was observed that the yarn increased markedly in bulk by forming a myriad of crimps or loops along thelength of the material; 1 For control purposes, samples of the original yarn were subjected to allthe steps-described above except stretching. That is, the yarn was treated with formic acid solution, dried, twisted with a similar yarn, and contacted with steam.

The yarn treated in accordance with the invention and the control yarn were then tested as follows: The yarns were subjected to a constant rate of elongation (about 100% per min.) while measuring the elongation and'the forceresisting the elongation. The results are tabulated below- 4 Example."

Wool yarn was'passed through atube into which. steam was injected. During its passage through the tube, the yarn was stretched to of itsoriginal length. While maintaining the stretch, the yarn was dried by passage under infra-red lamps. The set-strctchedyarn was then plied with untreated wool yarn. The composite yarn was exposed to .contact with steam and itwas noted that the yarn assumed its original length and formed a bulky yarn'displaying a multitude of loops and crimps along its length.

Having thus described the invention, what is claimed 1. The method which comprises subjecting wool yarn to the action of a swelling agent, stretching the swelled yarn, setting it in the stretched state, plying the setstretched yarn and other yarn to form a. multiple-ply yarn, and'relaxing thelcomposite yarn while untensioned to form a yarn of substantially greater bulk than the original composite yarn.

2 The method which comprises subjecting wool yarn to the action ofaqueous formic acid to swell the fibers, stretching the swelled yarnto about from 110 to of its original yength, drying the swelled and stretched yarn while under-tension to set the stretch, combining the set-stretched yarn with other yarn to form a multiple-ply yarn, andrelaxing the composite yarn while untensioned to form a yarn of substantially greater bulk than the original composite yarn.

3. The method which comprisessubjecting wool yarn to the action of steam to swell'the fibers, stretching the swelled yarn to about from 110 to'l50% of its original length, drying the swelled and stretched yarn while under tension to set-it in the stretched state, plying the setst retched yarn with other yarn to form a multiple-ply yarn, and relaxing the composite yarn while untensioned to form a.yarn of substantially greater bulk than the original composite yarn.

References Cited in the file of this patent UNITED STATES PATENTS 

1. THE METHOD WHICH COMPRISES SUBJECTING WOOL YARN TO THE ACTION OF A SWELLING AGENT, STRETCHING THE SWELLED YARN, SETTING IT IN THE STRETCHED STATE, PLYING THE SETSTRETCHED YARN AND OTHER YARN TO FORM A MULTIPLE-PLY YARN, AND RELAXING THE COMPOSITE YARN WHILE UNTENSIONED TO FORM A YARN OF SUBSTANTIALLY GREATER BULK THAN THE ORIGINAL COMPOSITE YARN. 